Lightning arrester and method of making the same



Jan. 13, 1931. J. R. M FARLIN 1,733,437

LIGHTNING ARRESTER AND METHOD OF MAKING THE SAME Filed Feb. 11, 1924Patented Jan. 13, 1931 UNITED STATES PATENT OFFICE JOHN ROBERT MOFARLIN,0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO ELECTRIC SERVICE" SUPPLIESCOMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIALIGHTNING ARRESTEB AND METHOD OF MAKING THE SAME Application filedFebruary 11, 1924. Serial No. 692,144.

My invention is designed to provide an improved device for eifecting theready discharge to ground from a protected line or instrument ofcurrents, or other electrical manifestations of abnormal potential, suchas lightning, while preventing leakage of normal current to ground. Myimproved arrester is particularly adapted for the protection ofapparatus such as is connected with razlio antennae, but is alsosuitable for the protection of low voltage direct and alternatingcurrent circuits for operating signals, alarms and the like, for theprotection of apparatus connected to alternating current circuits of115, 230 volts or higher, or for general use.

Leading objects of my invention are to provide, in a simply constructedand inexpensive device, means for effecting and maintaining accuratepositioning of gap electrodes and nice adjustment of the air gap betweenthem, and to provide for the gap electrodes a secure- 1 I sealednon-conducting shell excluding tiierefrom dust, moisture or corrodinggases, with avoidance of the corrosion of the elec trodes and closure ofthe air gap commonly material, as bakelite, about the knurled or.

corrugated bodies of binding posts to form complementary shell sectionshaving air tight joints with the binding posts embedded therein, theshell sections being adapted for connection with one another to providean electrode housing containing an expansion chamber having a sealedperipheral joint. The binding post body and the gap electrode of eachshell section are connected together in telescoped relation and the gapface of the electrode positioned in predetermined relation to a fixedpoint of the shell section, and preferably with relation to the bearingsurfaces of shell lugs adapted to abut against bearing surfaces ofsimilar lugs of a complementary shell section to space the gapelectrodes and limit the pressure on the packing in the peripheral jointformed by the connec-; tion of two shell sections.

The characteristic features and advantages of my improvements will morefully a pear from the following description of a pre erred embodiment ofmy invention and the accompanying drawings in illustration thereof.

In the drawings, Fig. 1 is a vertical sectional view of an arresterembodying my improvements, the section upon which the view is takenbeing indicated by the lines 11 of Fig. 2; Fig. 2 is a bottom plan view,upon a reduced scale, of the upper casing section or cap; and Fig. 3 isa transverse sectional view taken on the line 3-3 of Fig. 1.

As illustrated in the drawings, my invention is embodied in a lightningarrester comprising a pair of easing sections or caps 1, 1' moulded fromplastic insulating composition, such as bakelite, and hardened. Eachshell section or cap has embedded therein while plastic the knurledorcurrugated body 2, 2 of a binding post 3, 3. The plastic compositionis expanded axially along the binding posts to form extended bearings orhubs 4, 4 closely interlocked with the binding posts and providingmoisture and air proof seals and rigid supports.

The shell section 1 contains a channel 5 adjacent to the peripherythereof and forming a seat for a packing ring 6. The shell section 1 isprovided with a peripheral wall or flange 7 having a lip 7 registeringwith and adapted to be engaged in the channel 5 against the packing 6.The shell section 1 has moulded integrally therewith the lugs 8,connected with the hub 4 by the radial reenforcing ribs 9, the lugshaving embedded therein the headed ends of bolts or rivets 10. The lugs8 are adapted to pass within the peripheral wall 7 into abuttingrelation with similar lugs 8 integrally formed with the shell section 1and connected with the lug 4: by radial reenforcing ribs 9. The lugs 8contain rivet holes 11, terminating exteriorly in counterbored sockets11' which provide seats for the fibre washers 12 over which the heads10' of the rivets 10 are spun. If desired, the sockets may be filledwith a suitable sealing compound, as wax.

The binding post bodies 2, 2' have axial sockets 13, 13' drilled thereinto provide seats for the knurled gap electrodes 14, 14' having fins orserrations 15, 15' of slightly larger external diameter than theinternal diameter of the sockets 13, 13; so that when the electrodes arepressed into the binding post socks they cut their way into the bindingpost stock and make a tight force fit therewith.

The external ends of the binding posts are milled to provide seats 16,16 and drilled and tapped to accommodate screws 17, 17, whereby line andground wires 18, 18 are secured to the binding posts. The arrester maybe conveniently fastened to a support by means of the strap or band 19engaged between the beads 20, 20.

In assemblin my improved arrester, after the moulded s ell sections havehardened with the binding post bodies and rivet heads embedded therein,the gap electrodes 14, 14' are first forced into the sockets 13, 13 andtheir gap faces positioned in predetermined relation to the bearingsurfaces of the respective lugs 8, 8', or other casing surfacesdetermining axial positions of the casing sections relatively to oneanother. Such positioning of the electrodes may be suitably effected byan indexing guide on the forcing press.

The air gap distance between the gap faces of the electrodes when thearrester is assembled is a function of the relationship betweensuch gapfaces and the indexing surfaces of the respective casing sections. Forexample,

when the respective gap faces are retracted relatively to the planes ofthe respective lugs 8, 8, the air gap between the electrodes in theassembled arrester will be the sum of the distances which the electrodefaces are retracted.

When the electrodes are properly set, the casing sections are telescopedtogether with the lugs 8, 8 in abutting alignment and the lip 7 engagingthe packing 6 in the channel 5. By upsetting the heads 10 of the rivetsagainst the washers 12, the casing sections are securely fixed togetherand form a moisture and gas tight chamber containing electrodesaccurately spaced in a very simple and economical manner.

Having described my invention, I claim: 1. A lightning arrestercomprising a tight shell containing a peripheral groove, a strap engagedin said groove, a plurality of binding posts containing aligned socketshaving closed outer ends and gap electrodes seated in the respectivesockets and permanently fixed relative thereto.

. 2. A lightning arrester comprising a housing, a binding post and a gapelectrode, said post and electrode being fixed together in telescopedrelation and oneof said members having a serrated surface engaging theother member in fixed relation thereto and said post having serrationsengaging said housing and extending transverselyto the serrations firstnamed.

sections having radial reenforcm ri s and abutting bearings, saidsections a so having hubs forming seats for aligned gap elec-.trodespermanently fixed relative to the re-v spective sections andspaced by the engagement of said bearings.

4. A lightning arrester comprising shell sections having members forminga joint between them' and an elastic gasket sealing said joint, saidshell sections aving abutting bearings limiting the pressure on saidgasket.

5. A li htning arrester comprising shell sections 0 hardened plasticmaterial moulded around aligned binding posts, and gap electrodestelescopically connected with said binding posts, one of said memberslast named having fins embedded in the material of the other, and saidelectrodes being spaced by the engagement of abutting bearings of saidshell sections.

6. A lightning arrester comprising conoidal shell sections of hardenedplastic material moulded around binding posts at the.

apexes thereof and having gap electrodes seated therein, said shellsections having abutting bearings adjacent their Eeripheries of andforming a tight joint therewith, said shell section having a peripheralflange and spaced lugs, a second moulded conoidal shell section having abinding post set therein at the apex thereof in alignment with saidbinding post first named, said-second shell sec tion having memberscoacting with said flange and spaced lugs abutting against said lugsfirst named, and aligned electrodes connected with the respectivebinding posts and spaced to form an air gap by the alignment of the lugsof the respective shell sections.

8. In a method of forming lightning arresters the step which consists inmoulding a plastic substance around a terminal to form a shell section,hardening the shell section, and pressing an electrode into telescopicrelation to said terminal until its gap face is in indexed relation to afixed part of said shell section.

9. The method of forming lightning arresters which comprises moulding'aplastic substance around a terminal to form a h0l-.

